Tube Amp Archive

pjd3 wrote: ↑Sat Oct 11, 2025 1:39 pm I certainly can make some comparisons over time on looking at the bias waveforms.

I would be very interested in knowing what your results will be!

Yes that’s the phone number I have been using . That IS strange that B.A.D. contact cannot be made through a phone call. Nothing in the news that suggests an interruption with BAD operations. Since BAD represents and manufacturers at least nine entities, perhaps looking into the other eight company...

Are you using the phone number associated with Boutique Amp’s Distribution?

BOUTIQUE AMPS DISTRIBUTION
5300 Harbor Street
Commerce, CA 90040
Phone: 323-277-4100
Fax: 323-277-4110

Since no one has yet commented on the layout, I’m going to assume that all should be good to go. The adjustable fixed bias circuit was my main concern. I think I’ll flip the location of the V1 grid resistors at the socket and moved them to the jacks. In a couple days I’ll submit a custom turret boar...

I want to rebuild my 6G3 clone, minus its tremolo circuit, with a new board and a revised grounding scheme. I created the illustration with the DIYLC program from Hoffman Amps/EL34 World. I would like if anybody could take a look at the illustration and evaluate the layout. The brown resistors are t...

Disconnected the coupling cap from V2 to the PI. Fed a 300 Hz signal at the grids of the PI. All I heard was pure tone. Maybe I should be using a different frequency? Great! Now - can you turn the level of the signal to the PI down, simulating a decaying note? Does that have a swirling fizzy note a...

Heard back from Hiwatt after sending the amp in under warranty. They say they found the problem—it was a bad AC/DC SMPS. Hopefully when the amp returns to me all will be well. Congrats! And for the electronically challenged, like me: Switch Mode Power Supply (SMPS): A power supply that uses a high ...

I have a tone generator app or software on my PC. I can transfer the signal from the PC's headphone jack to a guitar instrument cable and into the input jacks of the amp and program any frequency. But I don't understand how to " mute the stage before the PI, feed a signal into the PI " Never mind.....

Hmmm. I just dragged out another debugging technique that might help. Do you have a signal generator other than your finger or a guitar? Sometimes you can ground the grid of successive stages and inject a signal after the muted stage. In your case, you can't really mute stages because it's a fizz o...

Here’s another check out I used once to help find out that the amp had an oscillating issue I could not hear before I had a scope to confirm that . Measure what your output tubes are idling at current wise if you can and make note of that. Also hook up your voltmeter set for ac volts across your sp...

There is the occasional amp that does not respond to cut-solder-replace techniques. You might be nearing the point where an oscilloscope is necessary. Nearing the point? I think that I have been tripping over that “point” lately, ha ha! Even before I started this thread, I already was saying to mys...

Do the grounding stuff already mentioned, that's often the most difficult and most effective way to start. Grounding schemes will drive even very experienced engineers crazy at times especially in today's high-speed digital circuits. Yes, I did try the alternative grounding schemes that were sugges...

Shielded grid wires didn't change anything.

Bypassing the V2 stage reduced the fuzzies a tiny bit, while reducing gain and volume of course.

Could shielded grid wires for the output tubes counteract any possible oscillation? Yesterday I tried some of the suggestions posted on this thread, but the results are still the same: Grounded the unused pins of V2. Disconnected heater at pin 5 of V2. Verified feedback loop is negative. Separated s...

Almost forgot… The OT and speaker jacks are grounded at the speaker jack’s mounting holes. The rest of the circuit is grounded at one point to the chassis at the input jacks. There is a dark-horse issue lurking here. If the OT and speaker jacks contact the chassis at one place, and the rest of the ...